1. Technical Field
The present invention relates to memory devices and, more particularly but not exclusively, to comparing data stored by memory cells of a memory device.
2. Background Art
A content addressable memory (“CAM”) typically stores data in a plurality of memory locations. The CAM may include value-matching logic that compares input data against the stored data and generates an indicator signal identifying those memory locations where the input value matches a stored value. A value match often is called a “hit.” Such properties of CAM technologies have been increasingly available over the past two decades.
However, as successive generations of dynamic random access memory (DRAM), static random access memory (SRAM), etc. continue to decrease in scale and price, there is an attendant increase in demand for mechanisms, such as those of a CAM, to support efficient searching of such affordable, high-volume random access memory (RAM) types. The more wide and varied integration of device networking has also driven demand for such mechanisms.
Ternary CAM technology, which supports use of a “don't care” state in data comparisons, has been one improvement over basic binary CAM. However, the relatively large memory cell sizes of CAM devices, along with the attendant small storage capacity and expensive price, continues to be an impediment to the use of CAM in many use cases. The need for alternatives to CAM is demonstrated, for example, by the use of substitute software approaches to implement some version of CAM's memory search functionality.